textproduct: Rapid City

KEY MESSAGES

- Areas of fog and low clouds late tonight into Thursday morning across western SD.

- Areas of fog may redevelop Thursday night into Friday morning, mainly around the Black Hills foothills and adjacent plains.

- Mild and dry into next week, breezy at times.

UPDATE

Issued at 923 PM MST Wed Nov 11 2026

Forecast remains on track this evening with expected low cloud development and fog across northwestern South Dakota, along the Black Hills foothills, and east into the South Dakota plains. CAMs still suggest spotty coverage for the fog from Rapid City southward. Added fog into the forecast for Thursday night into Friday morning due to the easterly/southeasterly flow against the Black Hills. Slightly breezier winds may determine where it develops. CAMs suggest the fog will mainly anchor around the Black Hills foothills and portions of northeast Wyoming and northwest/southwest South Dakota.

DISCUSSION

(This Evening Through Wednesday) Issued at 1233 PM MST Wed Nov 11 2026

Upper air analysis shows upper ridging over the western third of the CONUS, with northwest flow continuing across the northern Plains. Surface analysis shows a stalled frontal boundary sitting roughly near the eastern CWA border. Temperatures across the NE WY/Wrn SD plains have reached into the lower 60s accompanied by NW winds gusting up to 25 mph. Quiet weather will extend into tonight as winds weaken and lows drop into the upper 20s to upper 30s. Models show the stalled front becoming a backdoor cold front as it slides westward late tonight into Thursday morning. Easterly winds will favor upslope flow, resulting in low clouds. Fog is also expected along with the low clouds, especially across NW SD. There is more uncertainty with the latest CAMs as to how far south or widespread the fog will be, but current thinking is it will at least affect the eastern Black Hills and adjacent plains. Fog should diminish by late Thursday morning, though low clouds may persist longer across northwestern to central SD. Winds will become southeasterly along and behind the front. Thursday highs will range from near 70F in NE WY west of the boundary to the mid 40s near the eastern CWA border. Upper ridging slowly moves eastward Thursday night into Friday. Not much change with the temps on Friday as the boundary remains stalled over the area, though some moderation is expected on both sides of the front. A weak trough is projected to cross the region toward the weekend. Warmer than average temperatures across the rest of the CWA will advect into central SD as southerly flow increases. Precip from this system will stay well south as a split-flow pattern is reinforced. Dry weather and above average temperatures continue into early next week.

AVIATION

(For the 18Z TAFS Through 18Z Friday) Issued At 1010 AM MST Thu Nov 12 2026

The fog causing IFR/LIFR conditions for western South Dakota will be burning off at the start of the forecast period. VFR conditions are expected to return for the afternoon. Fog is expected to develop in western South Dakota overnight and cause IFR/LIFR conditions. Winds are expected to remain calm before becoming gusty late Friday morning.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.